"We are entitled to get the information and get to the bottom of this cozy bromance between Donald Trump and Vladimir Putin," Kaine said.

This was the third day of campaign stops for Kaine in Pennsylvania. Senator Bob Casey says it's a real example of just how important the Keystone State, and especially southeastern Pennsylvania, is to both campaign.

"Now southeastern Pennsylvania, the region, is critical. And that's from Philadelphia, through the suburbs and here in the Lehigh Valley. I think it'll be the most critical part of the state," said Casey.

The Trump campaign released a statement specific to Kaine's campaign efforts in Pennsylvania.

It reads in part, "Do Pennsylvanians want open borders, amnesty and the same old Washington politicians running the White House or do we want to elect a proven business leader who will eliminate sanctuary cities, enforce our federal immigration laws and bring back jobs?"

Kaine admits Pennsylvania will be tough to win, but he remains optimistic.

"I'm here to tell you something: I've run eight races and I've won eight races, and I ain't gonna lose this one. "I'm not going to lose this one," said Kaine.